Screening Finds Fewer Colorectal Lesions in Blacks

Action Points

At an urban safety-net hospital, black men were less likely than white men to have advanced colorectal neoplasia detected by a screening colonoscopy.

Note that the rate for advanced colorectal neoplasia was numerically higher among black women versus white women, although the difference did not reach statistical significance.

At an urban safety-net hospital, black men were less likely than white men to have advanced colorectal neoplasia detected by a screening colonoscopy, researchers found.

In a cross-sectional study, the prevalence of advanced colorectal neoplasia was 5.7% for black men and 9.3% for white men (odds ratio 0.59, 95% CI 0.39-0.89), according to Paul Schroy III, MD, MPH, of Boston University, and colleagues.

The rate was numerically higher among black women versus white women (4.3% versus 3.5%), although the difference did not reach statistical significance after accounting for various risk factors (OR 1.32, 95% CI 0.73-2.40), the researchers reported in the July 2 issue of Annals of Internal Medicine.

"Our findings provide new evidence suggesting that disparities in access to screening and differential exposure to modifiable risk factors rather than genetic differences are largely responsible for the higher overall incidence of colorectal cancer among black persons, especially men," they wrote.

The results "highlight the need for strategies focused on increasing screening rates among black persons in settings where disparities exist," they added. "These strategies must not only address barriers to access (such as a lack of healthcare insurance) but also patient- and physician-level barriers to acceptance, adherence, and use."

Previous research has shown that black individuals are more likely than their white counterparts to receive a diagnosis of colorectal cancer and to die from the disease, but it remains unclear whether biological, genetic, or environmental factors explain the disparity.

Prior studies exploring rates of advanced colorectal neoplasia in black versus white patients have yielded mixed results, with some showing a higher rate among blacks and some showing no difference.

Schroy and colleagues further examined the issue in a population of 1,172 white patients and 1,681 black patients with average risk who were undergoing routine screening colonoscopy at a single urban, open-access, academic, safety-net hospital (Boston Medical Center).

The individuals had no other indications for colonoscopy. All completed a risk-assessment questionnaire. The study took place between 2005 and 2012.

Advanced colorectal neoplasia was defined as a tubular adenoma 10 mm or greater in size, any adenoma with villous features or high-grade dysplasia, any dysplastic serrated lesion, or invasive cancer.

Advanced disease was more common among white patients (6.8% versus 5.0%, P=0.039), driven by the higher rate among black versus white men.

"Although no statistically significant differences were seen between white and black women, our findings are inconclusive, presumably due to the low prevalence of advanced colorectal neoplasia in this subgroup," the authors wrote.

Among the patients with advanced colorectal neoplasia, blacks were more likely than whites to have proximal disease in the transverse colon, hepatic flexure, ascending colon, or cecum (52% versus 39%), although the difference fell shy of statistical significance after adjustment for age and sex (P=0.055).

"Future studies are warranted to better define the extent to which genetic or biological factors might explain the predilection for proximal disease among black persons," Schroy and colleagues wrote.

They acknowledged that their study was limited by the use of patients from a single center, possible selection and recall bias, insufficient statistical power for many of the subgroup analyses, and the potential for misclassification of race.

In addition, they wrote, "our selection criteria precluded a comparison of advanced colorectal neoplasia prevalence in persons younger than 50 years and cannot shed light on recommendations by some professional groups to initiate screening for black adults at age 45 years."

The study was supported by a grant to Schroy from the National Cancer Institute. One of his co-authors reported receiving a grant from the NIH.

Reviewed by Robert Jasmer, MD Associate Clinical Professor of Medicine, University of California, San Francisco and Dorothy Caputo, MA, BSN, RN, Nurse Planner

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